1. Field of the Invention
The present invention relates to a readable/writable disk, such as an optical disk, and a disk reading/writing device for performing reading and writing from and onto the readable/writable disk. More particularly, the present invention relates to techniques of chucking disks having different outer diameters by a common chucking mechanism and increasing the data area of a small-diameter disk by reducing the chucking area.
2. Description of the Related Art
FIGS. 8 and 9 show a known type of chucking mechanism that can chuck a plurality of disks having different diameters. Referring to these figures, a disk base 20 has an aligning shaft 21 at the center of its upper surface, and is rotated by a spindle motor 22. FIG. 8 shows a state of chucking a small-diameter disk 23, and FIG. 9 shows a state of chucking a large-diameter disk 24. Both disks 23 and 24 are focused by an optical pickup 25 from the side of the disk base 20.
Regardless of the diameter, the above small-diameter and large-diameter disks 23 and 24 respectively have lead-in areas 23a and 24a in which management information is written at a specific position at the inner periphery thereof.
The chucking area is determined so as to be optimal for the large-diameter disk 24. While a sufficient chucking area is ensured in the small-diameter disk 23, it makes up a larger proportion of the small-diameter disk 23, and the volume of data that can be stored is limited.
In view of the above problems in the small-diameter disk 23, it is possible to increase the volume of data that can be stored. However, since the optical pickup 25 for focusing the disk is placed on the side of the disk base 20 in the chucking state of the small-diameter disk 23 shown in FIG. 8, the movement of the optical pickup 25 toward the inner peripheral side is limited by the disk base 20. Consequently, it is difficult to enlarge the data area.
The present invention has been made in order to overcome the above problems, and an object of the invention is to provide a disk reading/writing device in which a chucking mechanism is structured so that the chucking area of a small-diameter disk is less than the chucking area of a large-diameter disk, and the disks are focused by an optical pickup that is placed on the side opposite a chucking surface.
Another object of the present invention is to perform reading and writing from and onto a small-diameter readable/writable disk in which the data area is enlarged by reducing the chucking area thereof.
In order to achieve the above objects, the present invention provides a disk reading/writing device wherein a chucking mechanism is structured so that the chucking area of a small-diameter disk is less than the chucking area of a large-diameter disk, and the disks are focused by an optical pickup placed on the side opposite a chucking surface.
The chucking area of a small-diameter disk of the readable/writable disks is set to be less than the chucking area of a large-diameter disk.
In the disk reading/writing device and the readable/writable disk having the above-described configuration, since the chucking area of the small-diameter disk is reduced, it is possible to place the chucking area closer to the inner periphery, to enlarge the data area of the small-diameter disk, and to increase the volume of data.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.